1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device equipped with a recessed field effect transistor having a T-shaped gate electrode and a MIM capacitor, and specifically to a method for manufacturing a semiconductor device that has no problem of lift-off properties and no corrosion of a T-shaped gate electrode, and can prevent the elevation of the parasitic capacitance of the field effect transistor.
2. Background Art
A conventional method for manufacturing a semiconductor device equipped with a recessed field effect transistor having a T-shaped gate electrode and a MIM capacitor will be described. First, a field effect transistor and a lower electrode of a MIM capacitor are formed on a semiconductor substrate. Then, the T-shaped gate electrode of the field effect transistor is coated with a protective insulating film. Next, a capacity insulating film of the MIM capacitor is formed so as to coat the field effect transistor and the lower electrode. Here, a SiO2 film is used as the protective film, and a SiN film is used as the capacity insulating film. Next, using the selection ratio of SiO2 and SiN, the capacity insulating film on the field effect transistor is etched back by a RIE process. Then, an upper electrode of the MIM capacitor is formed on the capacity insulating film.
By the conventional method, however, it is difficult to completely remove the capacity insulating film to the space under the T-shaped gate electrode. Therefore, there is a problem that the parasitic capacitance of the field effect transistor is elevated.
Alternatively, there is a method wherein the capacity insulating film of a MIM capacitor is formed in the state wherein a portion including the active region of a field effect transistor is coated with a sacrifice layer, and thereafter, the sacrifice layer is lifted off. However, when the capacity insulating film is formed by a p-CVD process or the like, since the capacity insulating film easily goes onto the sacrifice layer, there is a problem that the sacrifice layer is difficult to lift off.
A method wherein a MIM capacitor is formed in the state wherein after the T-shaped gate electrode is coated with a SiO2 film, and subsequently the SiO2 film is removed with buffered hydrofluoric acid has been proposed (for example, refer to Japanese Patent Laid-Open No. 7-235644). However, when Ti or Al is used as the T-shaped gate electrode, there is a problem that the T-shaped gate electrode is corroded by hydrofluoric acid.